Disruption to airports and traffic networks is expected to continue on Tuesday as another round of snow sweeps across parts of the country.
Up to 10cm is expected to fall on Tuesday morning in parts of Scotland and northern England and a further 2cm in East Anglia, followed by around 6cm in southern England during Tuesday evening, forecasters have predicted.
The heavy snow and frost have so far claimed the lives of seven people, including a postman who died while carrying out his rounds during the weekend's freezing temperatures, the Royal Mail confirmed.
John Bircham died on Saturday during his collection on Exmoor, Somerset, after 25 years of service as a postman.
It is thought a 25-year-old woman died after collapsing in the snow on her way home in sub-zero temperatures following a night out.
Bernadette Lee was discovered in the front garden of the house next to her sister's by a man walking his dog on Sunday at 7.30am in Church Meadows, Deal, Kent.
Kent Police are investigating the cause of death but there are reports she had no visible injuries and was found without a coat.
A man was killed in another weather-related incident when the car he was driving left the road and crashed into a tree on the A12 in Essex last night.
It comes after four people died in an avalanche as they descended Bidean Nam Bian in Glencoe on Saturday afternoon. A further two people survived.
Elsewhere, a teenager remains critically ill in hospital after being injured while sledging in Middlesbrough.
Overnight temperatures plummeted to as low as -11.3 in Buckinghamshire, -10 at Stansted Airport and -9 at RAF Mildenhall in Suffolk.
Heathrow Airport has already warned passengers to expect cancellations and delays Tuesday and Gatwick has also advertised delays on its website.
More than 200 flights were cancelled at Heathrow Airport on Monday, while other airports including Gatwick and Birmingham also experienced disruption.
The wintry conditions forced the closure of Robin Hood Airport near Doncaster along with the runway at East Midlands Airport.
Leeds Bradford Airport was also closed for a short period while snow was cleared.
Passengers were advised to check the status of their flights before travelling.
A Heathrow spokesman said: "Because Heathrow runs at almost 100% capacity there is no slack in the system and flights unfortunately have to be cancelled. Further cancellations are inevitable given the adverse weather conditions at other airports around Europe."
A forecaster for MeteoGroup, the weather division of the Press Association, said: "With more snow coming today, we can expect more disruption.
"This morning we will see up to 10cm in snow in Scotland, northern England and around 2cm in East Anglia followed by more snow this evening in southern England - maybe up to 6cm.
"Temperatures were very low overnight, as low as -11.3 in Buckinghamshire, and will be low again tonight with many places struggling to stay above freezing during the day.
"The rest of the week will see widespread frost and showers."
Trains were also affected by the severe weather yesterday with many services cancelled, and the heavy snow closed two major roads across the Pennines.
The cold weather led to thousands of children having an extra day off as hundreds of schools remained closed. In some cases, parents were asked to bring shovels to help clear paths to enable them to open.
Teenager Liam Stafford remains critically ill in hospital after hitting a tree while sledging in Flatts Lane Country Park, Normanby, Middlesbrough, on Monday.
The 16-year-old was flown by the Great North East Air Ambulance to the James Cook University Hospital in Middlesbrough suffering from head injuries.
East of England Ambulance Service also issued a warning after it was called out to attend at least a dozen sledging-related injuries.
While none was life-threatening, some children and adults sustained broken bones or head injuries requiring hospital treatment.
Another warning was given by London Fire Brigade, which told people to stay off the ice after being called to rescue two men who had fallen through frozen lakes to rescue their dog yesterday. Crews also rescued a child who was stuck on his sledge in the middle of a frozen lake.
The Met Office has issued severe weather warnings as rain falling on to frozen surfaces increases the risk of ice.
Amber warnings remain in place for heavy snow across the higher ground of north-east England and eastern Scotland while yellow warnings are in place for ice and snow across parts of South Wales and western England.
The AA said it was expecting Tuesday to be one of the busiest days for call-outs this winter, at more than 17,000.
Breakdowns were being reported at a rate of around 2,000 an hour with the busiest areas being the Midlands, London, the South West and the South East.
Speaking as he signed a memorial book to commemorate the lives of those killed in the Holocaust, David Cameron said he expected his youngest daughter, Florence, to make a snowman.
Discussing the snow that had settled in London, he said: "You never normally see, after a few days, the snow still on the trees.
"I was just talking to my two-year-old daughter and said that she has got to make a snowman this afternoon, while it's all still there ... the first time they see snow is an exciting moment."Suggest a correction